1. Field of the invention
The subject invention relates to golf club heads of the "wood" or hollow "metalwood" type, but including clubs of other suitable materials, wherein an object of the design is to move the center of gravity away from the striking face.
2. Prior Art
Golf club heads are generally designated as being "woods" or "irons". The primary difference, affecting performance, being that the "wood" types possess a center of gravity some distance behind the striking face.
The "woods" are further divided into generally solid types and hollow types. For purposes of this discussion I will refer to them as "woods" and "metalwoods" respectively.
The hollow "metalwood" head possesses greater axial inertia than the solid "wood" type because of its perimeter weighting but its center of gravity is more forward in a less advantageous position because of the necessity of strengthening the striking face.
The modern wooden club head of about seven ounces has a center of gravity approximately 1" behind the striking face. Some clubmakers utilize available excess weight by placing a backweight of about one ounce at the very back of the clubhead. This moves the center of gravity rearward about 1/4" as compared to the more common practice of placing the weight in the bottom center or at the sides for "heel and toe" weighting.
It is commonly supposed that this rearward center of gravity relates primarily to "gear effect" as described in O'Hara, U.S. Pat. No. 1,299,014 . This is not the case as "gear effect" is merely incidental to the force vector angle being improved as the center of gravity moves rearward. See FIGS. 1, 2 and 3.
The force vector angle is that angle formed by a line drawn from a point near the club head center of gravity to the point on the club face struck by the ball and a second line drawn from the point near the center of gravity, extending along the path of the swing and intersecting the club face at its approximate center.
The following is a list of misconceptions, embodied in the prior art, which when examined in the light of the subject invention, will explain the superior performance of said invention;
a. That the rearward center of gravity of "woods" is primarily related to "gear effect". PA1 b. That a center of gravity too far from the face, will cause too much "gear effect". PA1 c. That there is a value to "heel and toe" weighting in a "wood" type head. PA1 d. That the head will rotate around the center of gravity when struck away from said center of gravity. PA1 e. That a center of gravity lower than normal will necessarily drive the ball too high. PA1 f. That the shaft need not be considered in calculations of club head action at impact. PA1 g. That a normal ball strike pattern will coincide with the shape and orientation of a normal face.
While I do not claim that all clubmakers are suffering from all the foregoing misconceptions and half-truths, I have to assume that they all embrace some of them as they have never produced a club head of the configuration and weight distribution of the subject invention.
The "Rules of Golf" as promulgated by the U.S.G.A. require that the width of the club head, from the heel to the toe, be greater than the depth from face to back. Any easily measured difference will satisfy the rule.